A hydrogen-based hybrid system was designed and simulated using the renewable resources available in Chicago, IL. The simulation was based on the probabilistic model developed for the Hybrid2 simulation software. The system integrates a 6.5 kW(p) solar array and a 12 kW wind turbine with a 2 kW fuel cell, 8 kW electrolyzer, and 3 kW hydrogen gas compressor to meet a varying load with a mean of 1 kW. The hydrogen generated by the electrolyzer is stored in a large, high-pressure tank (22 m(3) volume). The stored hydrogen provides energy for the fuel cell to meet the load when the renewable energy is insufficient. The performance of the system is described in detail along with the probabilistic models needed to simulate the hydrogen-based components. Over a period of 1 year the energy produced by the renewable power generators exceeded the load by 160%, and the system did not require additional hydrogen or fossil fuel to consistently meet the load using a very small battery bank. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.